Evidence for nonmonotonic magnetic field penetration in a type-I superconductor

Abstract

Polarized neutron reflectometry (PNR) provides evidence that nonlocal electrodynamics governs the magnetic field penetration in a low- κ superconductor. The sample is an In film with a large elastic mean-free path. It is shown that PNR can resolve the difference between the reflected neutron spin asymmetries predicted by the local and nonlocal theories of superconductivity. The experimental data support the nonlocal theory, which predicts a nonmonotonic decay of the magnetic field. © 2008 The American Physical Society.